Field of the Invention
The present invention relates to the art of a torque converter having a damping device that supresses torsional vibrations by a reciprocating motion of a rolling mass, and especially to a torque converter having a damping device in which the rolling mass is protected by oil applied to the torque converter.
Discussion of the Related Art
JP-A-2012-77826 describes a torque converter having a vibration absorber in which a rolling mass is held in a kidney-shaped guide hole formed on an outer circumferential side of a support member as a rotary plate while being allowed to be oscillated within the guide hole by torque pulses applied to the rotating plate. The torque converter is provided with a lockup clutch and a lockup damper aligned coaxially, and said vibration absorber is disposed therebetween. According to the teachings of JP-A-2012-77826, a driven member of the lockup damper and a turbine runner are connected to a turbine hub through a rivet, and the support member of the vibration absorber is connected to an intermediate member of the lockup damper through another rivet. In addition, the driven member of the lockup damper, the turbine runner and the support member are connected to the turbine hub through a common rivet.
JP-A-2012-77827 describes a torque converter in which a lockup clutch is arranged coaxially with a lockup damper, and an absorber device having a similar structure as said vibration absorber is disposed therebetween. According to the teachings of JP-A-2012-77827, an intermediate member of a lockup damper is connected to a support member of a vibration absorber through a rivet, and the intermediate member and the support member are also connected to the turbine hub through the same rivet. Further, another rivet connecting the turbine runner to the turbine hub is disposed on a radially outside of the turbine hub. WO2013/161058 also describes a vibration damping device arranged in a torque converter. According to the teachings of WO2013/161058, an area of the rotary member where a rolling member is held to oscillate is hermetically covered by a casing member. In the vibration damping device taught by WO2013/161058, a driven member of a lockup damper and a turbine runner are fixed to a hub connected through a single rivet.
Thus, according to the teachings of JP-A-2012-77826 and JP-A-2012-77827, the lockup dampers individually comprise the intermediate member connected to the drive member through a spring in addition to the drive member and the driven member, and the support member of the vibration absorber is connected to the intermediate member. In those torque converters, the turbine runner and the driven member are connected to the turbine hub by the rivet, and the support member is connected to the intermediate member by another rivet. However, a conventional spring damper does not have the intermediate member, and if such conventional spring damper is employed in the torque converter, all of the driven member, the support member and the turbine runner have to be connected to the turbine hub. Given that those three members are fastened to the turbine hub using a common rivet, a long shaft of the rivet is required. In this case, the rivet may be buckled or deformed unintentionally by an impact to expand a tail of the shaft thereby loosening a connection among those members.
According to a vibration damping device taught by WO2013/161058, an oscillating motion of the rolling member will not be disturbed by the oil in the torque converter so that vibration damping performance can be ensured. However, a long rivet is required to connect the housing and the support member to the turbine hub to seal the housing liquid-tightly. In addition, a hermeticity test of the housing has to be carried out after fixing the housing to the turbine hub, the driven member and the turbine hub and this makes difficult to perform the hermeticity test. Further, if a test result shows that the hermeticity is insufficient, usable members such as the turbine runner, the driven member and the lockup damper have to be replaced together with the housing.
The present invention has been conceived noting the foregoing technical problems, and it is therefore an object of the present invention is to provide a torque converter in which a hermeticity test of a torsional vibration damping device can be carried out easily, and in which a plurality of members including the torsional vibration damping device can be attached easily to a turbine hub.